1. Field of the Invention
The present invention relates to a record medium such as various types of optical disks and a method of controlling access to the record medium.
2. Description of the Related Art
Recently, an optical-disk record medium having a large storage capacity and portability has been commonly used as a record medium for a PC (Personal Computer). A typical recordable optical-disk record medium is, for instance, a CD-R (CD Recordable), a CD-RW (CD Re-Writable), or the like. In addition, a CD-ROM (CD Read Only Memory) is widely used as a read-only type record medium.
Information recorded on a record medium such as the CD-R or the CD-RW can possibly be information created by an owner of the record medium for the purpose of limiting access to the information to the owner or specific users. Additionally, highly important information such as confidential information of a company can possibly be recorded on the record medium. Accordingly, damage caused by a loss of the record medium or an unauthorized usage of the record medium by a third party is immense.
On the other hand, it has become important to prevent illegal copy of information recorded on a CD-ROM, by considering a copyright of the information.
Various suggestions have been made against the unauthorized usage of the record medium. For example, according to Japanese Laid-open Patent Applications No. 5-257816 and No. 6-295521, a usage-permission key or a one""s own number key is provided to information such as a program or data recorded on a recoding medium, or the information is coded, for preventing an unauthorized access to the information or an illegal copy of the information.
Additionally, Japanese laid-open Patent Applications No. 11-134650, No. 11-134719 and No. 11-134813 disclose measures devised to deal with an unauthorized access to information recorded on a record medium or an illegal copy of the information. Such measures are applied to a method of recording the information on the record medium and an information recording/reproducing device, according to the Japanese laid-open Patent Applications No. 11-134650, No. 11-134719 and No. 11-134813.
However, a record medium is often installed or mounted in a data processing device such as a PC including an operation system, in fact. The condition is which the record medium is installed in the data processing device is a condition in which information can be reproduced from or can be recorded to the record medium through a drive device, since fixed information such as root-directory accessing information defined as a regular file system is recorded at a fixed location on the record medium. In other words, by controlling the drive device used for reading information from or writing information to the record medium, one can access the information recorded on the record medium.
Accordingly, the former methods of preventing the unauthorized usage of the record medium suggested by Japanese Laid-open Patent Applications No. 5-257816 and No. 6-295521 are not quite effective. Additionally, for example, an analysis on an encoding algorithm about encoded information enables the unauthorized usage of the information supposed to be protected originally.
On the other hand, the latter methods suggested by Japanese laid-open Patent Applications No. 11-134650, No. 11-134719 and No. 11-134813 cannot be applied to an information recording/reproducing device that has been already out in the market. Thus, such methods needs time to be achieved. In addition, a new information recording/reproducing device must be introduced so as to achieve the latter methods.
Accordingly, it is a general object of the present invention to provide a record medium and a method of controlling access to the record medium. A more particular object of the present invention is to provide a record medium and a method of controlling access to the record medium, which allow a specified user provided with a predetermined disclosure level to access to information corresponding to the disclosure level, provided that specified users can use information recorded on the record medium in a general environment such as a personal computer using the record medium.
The above-described object of the present invention is achieved by a record medium including a plurality of root-directory data, each root-directory datum indicating a different part of a directory structure of the record medium.
The above-described object of the present invention is also achieved by a method of controlling access to a record medium including a plurality of root-directory data, root-directory accessing information that is defined as a regular file system, and a plurality of root-directory location data indexed by a plurality of disclosure levels, wherein one of the plurality of root-directory data indicates only a root directory, each of the other root-directory data indicates a part of a directory structure of the record medium, the part corresponding to a disclosure level, the root-directory accessing information includes information used for accessing the one of the plurality of root-directory data, and each of the plurality of root-directory location data is used for accessing the other root-directory data in accordance with the disclosure level, the method including the steps of deciding whether a user is authorized to access to the record medium when the user tries to access the record medium; analyzing the disclosure level inputted by the user; accessing the root-directory datum corresponding to the disclosure level inputted by the user, by following the root-directory location datum in accordance with the disclosure level, thereby allowing the user to access to information recorded in the part of the directory structure indicated by the root-directory datum; and allowing the user to access to the one of the plurality of root-directory data indicating only the root directory, by following the root-directory accessing information, if the user is unauthorized.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.